1. Field of the Invention
The present invention generally relates to an image data recording system for receiving an optical image incident upon an image recording system through a lens, for converting the received optical image into electronic image data, and for storing the electronic image data therein. More specifically, the present invention is directed to an image data recording system utilizing memory cards to store the electronic image data.
2. Description of the Related Art
As an image data recording system, a so-called xe2x80x9celectronic still cameraxe2x80x9d has been practically marketed. In the commercially available electronic still cameras, still images are optically and electrically processed to be stored in a recording medium, for instance, a magnetic disk.
More specifically, in the conventional electronic still camera, a semiconductor imaging element, e.g., a charge-coupled device (referred to as a xe2x80x9cCCDxe2x80x9d) is employed to optically receive a still image and convert it into a corresponding electronic image signal. After the electronic image signal is processed to have a signal format suitable for a television signal, the processed image signal is modulated into an FM (frequency modulation) image signal. Then, the FM image signal is recorded onto a magnetic disk in an analog signal form. If such an electronic still camera records the FM image signals with a field recording format, 50 still pictures or complete images can be recorded on a magnetic disk.
In such a conventional magnetic disk type electronic still camera, miniaturization of the electronic still camera meets with practical difficulties, because there is a size limitation to manufacture of a compact driving mechanism for driving the magnetic disk.
Accordingly, to solve these difficulties of the conventional magnetic disk type electronic still camera, another type of electronic still camera employing a built-in semiconductor memory (referred to as a xe2x80x9cRAMxe2x80x9d) has been recently developed, in which an analog still image signal is processed to obtain a digital still image signal. The digital still image signal, or digital image data is stored in the built-in semi-conductor memory (RAM).
However, the semiconductor memory type electronic still camera has another drawback. In general, when a single still image is stored into a semiconductor memory, a memory capacity of more than 2 M bits (mega bits) is required for each still image. Therefore, to store 50 still pictures (or images) in such a semiconductor memory type still camera, which is similarly performed in the magnetic disk type still camera, a semiconductor memory having a memory capacity of more than 100 M bits is required. However, a semiconductor memory type still camera having such an extremely high memory capacity is not practically available.
The present invention has been accomplished in an attempt to solve the problems mentioned above. An object of the invention is therefore to provide a still image recording system wherein a compact camera body can be realized and a relatively large quantity of still images can be temporarily or permanently stored in a detachable memory unit.
To achieve the above-described object of the invention, an image data recording system of the present invention comprises: a housing means; optical means arranged at least partly in the housing means, for forming an optical image on a predetermined plane in the housing means; image data processing means arranged in the housing means for producing digital electronic image data in response to the optical image; memory means detachably mounted to the housing means and electrically coupled to the image data processing means when mounted to the housing, means, for storing the digital electronic image data therein; output terminal means arranged in the housing means and being coupled for outputting the digital electronic image data derived from the detachable memory means when the detachable memory means is mounted to the housing means; and control means arranged in the housing means, for controlling a writing operation of the digital electronic image data into the detachable memory means when the detachable memory means is mounted to the housing means, and for controlling a reading out operation of the digital electronic image data to the output terminal means from the detachable memory means when the detachable memory means is mounted to the housing means.
According to a further feature of the invention, a peripheral memory means, arranged outside of the housing means, is detachably coupled to the output terminal means, for storing the digital electronic image data therein which was read out from the detachable memory means and which was output from the output terminal means.
A display means is preferably coupled to at least one of the output terminal means and the peripheral memory means, for displaying an image representative of the digital electronic image data which was stored in the detachable memory means.
After the digital electronic image data is read out from the detachable memory means and stored in the peripheral memory means (such as a video tape recorder), the detachable memory means can be re-used or erased and stored for later re-use.
The detachable memory means may be memory cards each containing at least one semiconductor memory chip, or other detachable memory card-like devices.
With the above-described arrangements of the still image recording systems according to the present invention, a compact and portable electronic still camera can be obtained, since a disc drive mechanism is not needed. In addition, the effective memory capacity of the system using detachable semiconductor memory units is equal to, or higher than, that of the conventional electronic still camera using RAM memory in the conventional manner or using the conventional disc drive arrangement.